1. Field of the Invention
The present invention relates to an image forming apparatus including an optical scanning device.
2. Description of the Related Art
In electrophotography image recording, an image forming apparatus using laser light is widely used. In this case, the image forming apparatus generally includes an optical scanning device, and forms a latent image on a surface of a drum-shaped photosensitive element by scanning the photosensitive element with a light flux output from a light source in an axial direction of the photosensitive element using a deflector (for example, a polygon mirror) while rotating the photosensitive element.
In the image forming apparatus, the light amount of scanning light may change due to a change in temperature or an elapse of time, and density unevenness may occur in an image. To suppress this, in a general optical scanning device, a part of light output from a light source is received by a detector such as a photo diode as a light flux for monitoring, and auto power control (APC) for controlling the output level of the light source is performed based on the result (see for example Japanese Patent Application Laid-open No. H9-288244, Japanese Patent Application Laid-open No. 2002-40350, and Japanese Patent Application Laid-open No. H4-321370).
However, a demand for capability of forming a higher quality image of an image forming apparatus is growing. Therefore, the apparatus disclosed in Japanese Patent Application Laid-open No. H9-288244, Japanese Patent Application Laid-open No. 2002-40350, and Japanese Patent Application Laid-open No. H4-321370 will not provide sufficiently accurate APC control, therefore it will be difficult for the apparatus to meet the demand.